Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/05—Alcohols; Metal alcoholates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
  • C08L83/06—Polysiloxanes containing silicon bound to oxygen-containing groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
  • C08G77/16—Polysiloxanes containing silicon bound to oxygen-containing groups to hydroxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
  • C08G77/24—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen halogen-containing groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/70—Siloxanes defined by use of the MDTQ nomenclature

Definitions

• This invention relates to silicone sealants which cure upon exposure to moisture without releasing corrosive by-products.
• One of the types of one component room temperature curing silicone rubbers is that disclosed by Weyenberg in United States Patent No. 3,334,067, issued August 1, 1967.
• This composition of hydroxyl endblocked polydiorganosiloxane, silane of the formula R′Si(OR ⁇ )3 and chelated titanium compound is stable in the absence of moisture, but cures upon exposure to moisture.
• Compositions such as these have been developed into commercial sealants which are promoted for filling openings in buildings to seal them from the weather.
• a successful sealant for such applications must adhere to the substrate on which it is placed in order to form a reliable seal.
• Many different types of sealants have been made available with varying degrees of adhesion to various types of substrates such as are found in buildings. Improving the adhesion of such sealants to a wider variety of substrates has been the object of much experimentation.
• This invention is a composition consisting essentially of (A) 100 parts by weight of a hydroxyl endblocked polydiorganosiloxane having a viscosity of between 1.0 and 100 Pa ⁇ s at 25°C, the organic groups being selected from the group consisting of methyl, ethyl, propyl, phenyl, and trifluoropropyl, (B) from 0.35 to 9.0 parts by weight of an alkyltrialkoxysilane of the formula RSi(OR1)3 where R is a monovalent hydrocarbon radical of from 1 to 4 carbon atoms and R1 is an alkyl or alkoxyalkyl radical, (C) from 0.2 to 3.0 parts by weight of titanium catalyst, (D) from 0 to 250 parts by weight of filler, (E) from 0.1 to 2.0 percent by weight of the sum of A, B, C, and D of a silane of the formula (MeO)3SiCH2CH2CH2NHCH2CH2NH2, and (F) from
• the composition of the instant invention contains hydroxyl endblocked polydiorganosiloxane having a viscosity of between 1.0 and 100 Pa ⁇ s at 25°C.
• the organic groups of the polydiorganosiloxane are selected from the group consisting of methyl, ethyl, propyl, phenyl, and trifluoropropyl.
• the preferred organic group is methyl since this is the most economical at the present time. If solvent resistance is a requirement of the cured elastomer, up to 50 mol percent of the organic groups can be trifluoropropyl groups.
• the viscosity of the polymer is greater than 1.0 Pa ⁇ s at 25°C because polymers having a lower viscosity do not give satisfactory physical properties.
• the viscosity of the polymer is less than 100 Pa ⁇ s at 25°C because polymers having higher viscosities, for example, 1,000 Pa ⁇ s at 25°C result in compositions which are too viscous to be readily extruded from the common storage tubes used for sealants.
• the polymer can be a homopolymer or a copolymer or mixtures.
• the viscosity of the polymer is the average viscosity of the polymer or polymers used as (A).
• the polymer can have a wide variation of molecular weights of individual molecules present as long as their average viscosity is within the claimed range.
• the preferred viscosity is from 40 to 60 Pa ⁇ s at 25°C.
• the alkyltrialkoxysilane (B) is the crosslinking agent of the average formula RSi(OR′)3 where R is a monovalent hydrocarbon radical of from 1 to 4 carbon atoms and R′ is an alkyl or alkoxyalkyl radical. Suitable silanes or mixtures of silanes are well-known in the art. R is preferably methyl, vinyl, or ethyl, with methyl being the most preferred radical. R′ is preferably methyl, ethyl, or methoxyethyl, with methyl being the most preferred radical.
• the crosslinker (B) is used at a level of from 0.35 to 9.0 parts by weight.
• the composition requires at least 2 mols of crosslinker per mol of hydroxyl in the polymer (A).
• crosslinker it has been found that it is preferred to use up to 5 times excess of crosslinker to provide for the reaction of some of the crosslinker with incidental hydroxyl groups present in the composition, for example on the filler, and to react with moisture which may be present in the composition when it is produced or which may gain access to the composition during storage.
• the titanium catalyst (C) is selected from the well-known titanium catalysts used in silicone moisture-­ curing sealants such as tetrabutyltitanate, tetraisopropyl­titanate, and the chelated titanium compounds such as those disclosed in U.S. Patent No. 3,334,067, issued August 1, 1967, to Weyenberg, and U.S. Patent No. 3,499,859, issued March 10, 1970 to Matherly, both of which show suitable titanium catalysts and their method of manufacture.
• a preferred catalyst is 2,5-diisopropoxy-bis-ethylacetoacetate titanium.
• the composition of the present invention can be modified by the incorporation of various reinforcing and extending fillers.
• Suitable fillers are those well-known fillers used in silicone polymers such as fume silica, precipitated silica, diatomaceous earth, calcium carbonate, zinc oxide, titanium oxide, iron dioxide, and ground quartz.
• the fillers may be untreated or treated with surface treatments either before addition to the composition or treated in situ during the manufacture of the composition.
• the most useful fillers are calcium carbonate alone, or mixed with fume silica.
• the preferred amount of filler is from 10 to 200 parts by weight. From 1 to 20 parts of reinforcing filler is preferred and from 1 to 200 parts of extending filler. A combination such as from 5 to 15 parts of reinforcing filler and from 150 to 200 parts of extending filler is most preferred.
• Ingredients (E) and (F) are added to the composition to aid in adhering of the cured composition to a wide variety of substrates. It was found that the addition of an additive to improve adhesion, such as (E) (MeO)3SiCH2CH2CH2NHCH2CH2NH2 was not satisfactory in many cases. For example, when a composition containing (E) as adhesion additive was cured in contact with ACT reflective glass or Duranar coated aluminum, there was zero percent cohesive failure when the sealant was peeled off the substrate after 14 days at room temperature. When immersed in water for 7 days and then tested for adhesion, the sample showed zero percent cohesive failure when tested against an anodized aluminum substrate.
• an additive to improve adhesion such as (E) (MeO)3SiCH2CH2CH2NHCH2CH2NH2
• the amount of ingredient (E) is from 0.1 to 2.0 percent by weight of the remaining composition, not containing (E) and (F). If less than this amount is used, the improved adhesion is minimal. More than this amount can be used, but it is unnecessary because this amount already gives 100 percent cohesive adhesion.
• the preferred amount of (E) is from 0.1 to 0.5 parts by weight.
• the amount of ingredient (F) is from 0.15 to 2 percent by weight of the remaining composition, not containing (E) and (F). If less than these amounts is used, the improved adhesion is minimal. More than this amount can be used, but it is unnecessary because this amount already gives 100 percent cohesive adhesion.
• the preferred amount of (F) is from 0.15 to 0.5 part by weight.
• Additional ingredients such as flame retardants, stabilizing agents, plasticizers, and pigments may be added as long as they are evaluated to ensure that they do not adversely effect the adhesion of the composition.
• the composition of the present invention is produced by mixing, in the absence of moisture, ingredients (A), (B), (C), (D), (E) and (F), then storing the mixture in the absence of moisture.
• a preferred method mixes the polymer (A), filler (D), and any filler treating agent or plasticizer, then heats the mixture with stirring to a temperature of greater than 100°C under vacuum or under a nitrogen sweep to thoroughly disperse the filler and to remove any excess moisture. Then the mixture is cooled without exposure to moisture and the crosslinker (B) and catalyst (C) are added without exposing to moisture. Then (E) and (F) are added, again without moisture exposure as silanes will react when exposed to moisture. The finished mixture is then stored in moisture-proof containers, for example, the common sealant cartridges used to store and apply sealants.
• the improved composition of this invention is particularly useful in the manufacture of modern, glass-walled buildings when it is necessary to obtain reliable sealing of the joints between reflective glass panels on the metal-supporting structures which are generally treated to give a weatherproof surface.
• compositions useful as sealants were prepared to determine their adhesion to a variety of substrates.
• a base composition was prepared by admixing 30.2 parts of a hydroxyl endblocked polydimethylsiloxane fluid having a viscosity of about 48 Pa ⁇ s at 25°C and a hydroxyl content of about 0.06 percent by weight, 53.4 part of calcium carbonate having a surface treated with calcium stearate, 9 parts of a trimethylsiloxy endblocked polydimethylsiloxane fluid having a viscosity of about 0.1 Pa ⁇ s at 25°C, 3.8 parts of fumed silica having a surface area of about 150 m2/g, and 1 part of a hydroxyl endblocked polymethylphenylsiloxane having a hydroxyl content of about 4.5 weight percent and a viscosity of about 0.5 Pa ⁇ s at 25°C.
• This mixture was then mixed, in the absence of moisture, with 2.6 parts of a second mixture of 73.5 parts of methyltrimethoxysilane, 24.5 parts of 2,5-diisopropoxy-bis-ethylacetoacetate titanium, and 2 parts of 3-(2-aminoethylamino)propyltrimethoxy silane. The mixture was then placed under vacuum to remove entrapped air and any volatile materials.
• compositions were then prepared by mixing, in the absence of moisture, 100 parts of the above base with 0.5 part and 1.0 part of additives.
• Additive A was an epoxy functional silicone fluid having the formula
• Additive B was an epoxy functional silicone fluid of the formula
• Additive C was an epoxy functional silicone fluid of the formula After mixing, each composition was placed in a sealant cartridge for storage. A seven-day period was allowed for any reaction that might take place to reach equilibrium, then test samples were prepared.
• the samples were then placed into room temperature tap water for 1 day and the adhesion was re-evaluated. The sample was returned to the tap water and adhesion was again evaluated after 7 days total in water.
• Each sealant sample was also tested for physical properties by tooling a sheet of sealant onto polyethylene coated paper, allowing the sheet to cure for 21 days at standard laboratory conditions, cutting out test samples and testing with a durometer in accordance with ASTM D2240, tensile strength and elongation at break in accordance with ASTM D412, and tear strength, die B, in accordance with ASTM D624.
• the skin-over-time (SOT) and tack-free-time (TFT) of each sealant when exposed to moisture under the standard laboratory conditions were also measured. These results are shown in Table II.
• ACT glass is a commercial reflective coated glass from Advanced Coatings Technology consisting of a vacuum spreader applied nickel chromium coating.
• Duranar is a fluorocarbon finished aluminum from PPG. Both mill finished and anodized aluminum were tested as well as concrete.
• composition containing additive C was the only composition that adhered to the ACT glass substrate. All samples adhered to the anodized aluminum and mill finished aluminum. Additive C gave adhesion to the Duranar substrate at the 0.5 level, while the other additives required the 1 percent level. None of the additives provided successful adhesion to concrete after the 7 day immersion in water.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Sealing Material Composition (AREA)

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Cited By (6)

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• 1986
  • 1986-07-30 CA CA000514940A patent/CA1283494C/fr not_active Expired - Lifetime
  • 1986-08-29 DE DE8686306680T patent/DE3682876D1/de not_active Expired - Fee Related
  • 1986-08-29 EP EP86306680A patent/EP0221644B1/fr not_active Expired - Lifetime
  • 1986-10-14 AU AU63889/86A patent/AU585398B2/en not_active Ceased
  • 1986-10-15 JP JP61243334A patent/JP2561250B2/ja not_active Expired - Fee Related

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